Brewing tea removes lead from water
The brewing process passively removes toxic heavy metals from drinking water
A recent study by Northwestern University researchers demonstrates that brewing tea can naturally remove heavy metals, including lead, from water.
This occurs through adsorption, where metal ions stick to the surface of tea leaves and remain trapped.
While the researchers do not suggest using tea as a dedicated water filter, their findings highlight tea's passive ability to reduce heavy metal exposure simply through normal consumption.
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Tea leaves effectively adsorb metals due to their high surface area, which enhances their ability to bind contaminants.
Other materials could achieve similar results, but tea is particularly significant because it is the most widely consumed beverage in the world, requiring no extra effort from consumers to benefit.
The research team tested various tea types, including black, green, oolong, white, chamomile, and rooibos, as well as loose-leaf and commercially bagged tea. They prepared water solutions with known concentrations of lead and other metals, heated them to just below boiling, and steeped the tea for different durations, ranging from seconds to 24 hours.
By comparing metal levels before and after steeping, they determined how much contamination was removed.
One key finding was the importance of tea bag material. Cellulose-based tea bags, made from wood pulp, removed the most heavy metals due to their high surface area, providing more binding sites for metal ions.
In contrast, cotton and nylon tea bags removed negligible amounts of contaminants. Moreover, nylon tea bags are problematic as they release microplastics, whereas cellulose tea bags only release biodegradable fibers, which the body can process safely.
The study also found that the type and grind of tea had some influence. Finely ground tea leaves, particularly black tea, removed slightly more metal ions than whole leaves because processing increases surface area by creating wrinkles and pores.
However, the most critical factor was steeping time. Longer steeping periods led to greater metal adsorption, with overnight steeping being the most effective. While tea brewed for only a few seconds removes minimal contaminants, extended brewing—such as for iced tea—can significantly reduce or nearly eliminate metal content in water.
